Since almost all forms of life need water to survive, the improvement of water quality in decontamination systems has typically been a subject of significant interest. As a result, treatment systems and techniques for removing contaminants from contaminated fluids have been developed in the past. Prior approaches have included water treatment by applying various microorganisms, enzymes and nutrients for the microorganisms in water. Other approaches involve placing chemicals, such as chlorine, in the contaminated fluids in an effort to decontaminate supplies. Some such systems have proved to be somewhat successful; however, severe deficiencies in each approach may still be prominent. In some prior systems, solid reactants are used that have to be dissolved or dispersed prior to use, or were cumbersome and not particularly suited for prolonged water treatment, or could not be used in a wide variety of different types of applications. In particular, the handling of the solid reactants often posed problems with respect to different dissolution rates, concentrations and growth rates. In addition, in systems employing chemical additives, the resulting “decontaminated” fluid may actually now be contaminated by these chemicals, in spite of having removed the original biological or other contaminants from the media. Even in systems employing micro filtration, problems with the system may not be from any sort of additive, but instead may simply be the clogging of the filter elements or membranes with foulants accumulated from the decontamination process. Time-consuming filter cleaning processes combined with system downtime can become costly and inefficient for purification companies.
One approach to treating surface waters and other contaminated fluids is to coagulate water-borne contaminants with suitable coagulants such as ferric chloride, poly-aluminum chloride, alum, or other coagulants known in the art. Chemical coagulants change the surface charge of contaminants, which reduces the repelling force between the contaminants. As such, the coagulants allow the contaminants to collide and coagulate together into larger flocs. Larger particles can still be formed by adding suitable polymers into the contaminated fluid. The polymers form bridges between the flocs to form large agglomerates. The large agglomerates settle with gravity and may be removed by a clarifier or a filter.
Some treatment processes may include modifying the pH of the contaminated fluid prior to adding the coagulants because some coagulants operate best within a specific pH range. For example, some ferric-based coagulants may operate best at reduced pH levels, which may require adding acids to the contaminated fluid. Other coagulants may operate best at specific alkalinities, which may require adding bicarbonate or acids depending on whether the alkalinity is too low or high. In some cases, the addition of the coagulant itself may affect the pH, and neutralization may be required.
Another approach to treating contaminated fluid uses ion exchange to exchange benign molecules with contaminants of concern. An example is the removal of hexavalent chromium. Once the exchange sites of the ion exchange media is spent, the regeneration of the exchange media creates a large volume of brine containing the contaminants of concern.
As used herein, “contaminated fluid” is a fluid that contains undesirable organic, inorganic products, metals, and possibly microbial cells or other microorganisms. Although contaminants are undesirable in the sense that they are usually toxic when ingested or contacted by humans, the term “undesirable” should not be understood to be restricted to such toxic substances.